Carrier route record

F9DEN→PDX

Frontier Airlines · Denver to Portland

Flights: 311
Period: July 2025 to June 2026
Share of route: 7%
Carriers: 5

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Frontier Airlines.

Frontier on DEN to PDX lands a B+, 3 points better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 311 flights. The strongest carrier on the route with a full sample, United Airlines, flew 1,821 at 81.7% on time.

United Airlines is the most reliable of the three carriers covered here at 81.7% on time across 1,821 flights.

On time

80.3%

Arrivals under 15 minutes late, of 309 completed flights

Avg delay

69 min

Across delayed arrivals only, not all flights

Cancelled

0.64%

National rate is 1.81%

Whole route

73.9%

Every carrier on DEN to PDX, 4,289 flights

These figures cover 311 flights between July 2025 and June 2026. The median arrival is 5 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.

Carrier by carrier

Frontier against every carrier on DEN to PDX

Frontier flew 311 of the 4,289 flights on DEN to PDX, about 7% of it. Its 80.3% on time is 6 points better than the route as a whole, which runs 73.9%. Ranked by on-time rate it is number two of five carriers on the route, where the range runs from United at 81.7% to SkyWest at 46.2%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The choice of carrier is not cosmetic here. United Airlines arrives on time 81.7% of the time; Southwest Airlines manages 62.5%. Sample sizes sit next to every figure, because a two-point gap across 1,563 flights means less than a ten-point one.

On-time performance by carrier on DEN to PDX
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	1,821	81.7%	60 min	0.44%	B+
Frontier Airlines (this page)thin sample	311	80.3%	69 min	0.64%	B+
Alaska Airlines	581	77.5%	55 min	0.69%	B+
Southwest Airlines	1,563	62.5%	47 min	0.32%	D+
SkyWest Airlinesthin sample	13	46.2%	42 min	0.00%	F+

The spread between United and Southwest is 19 points, wide enough that it should decide the booking. On a hundred trips that is 19 more arrivals inside the on-time window.

Departure window

When Frontier runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 21 points, against 19 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am—
8am–11am153 flights83.7%
11am–2pm14 flights—
2pm–5pm47 flights89.4%
5pm–8pm—
8pm–5am97 flights68.4%

Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.

The best window here is not the first bank but the 2pm–5pm slot at 89.4% on time, ahead of 8pm–5am at 68.4%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 8am–11am window is the busiest, with 153 flights scheduled in it.

Across the year

Frontier on DEN to PDX through the year

Jul–Sep 2025149 flights74.1%
Oct–Dec 202567 flights85.1%
Jan–Mar 202623 flights—
Apr–Jun 202672 flights87.5%

Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 80.3% on time across 311 flights.

Frontier on DEN to PDX did not run the same all year. Its best quarter was Apr–Jun 2026 at 87.5% on time and its weakest Jul–Sep 2025 at 74.1%, a swing of 13 points on roughly 104 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Across the week, Wednesday is the strongest day at 90.3% on time and Monday the weakest at 70.2%. 20 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Frontier runs late on this route

Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 4,208 reported delay minutes.

Carrier
39%
Late-arriving aircraft
36%
National Airspace System
20%
Extreme weather
4%

36% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 4,208 reported delay minutes here, that single category outweighs weather by 9 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 4,208 reported delay minutes.

The largest share of delay minutes, 39%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 1,658 of the 4,208 delay minutes reported here.

Cancellations are rare at 0.64%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.

Connections and stage length

What a delay here costs

7.8% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last a little over an hour, which a normal layover absorbs.

The 991 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

The return leg is a different operation and performs like one: it runs 77.3% on time across 312 flights, 3 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 3 points of difference.

One caution: this is a thin sample. 311 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.

What to do with this

Booking Frontier on DEN to PDX

Put together: treat all of this as provisional. 311 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 80.3% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 309 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures